There are many instances where the use of electronic flash as the light source in photography is advantageous. However, in all but the most routine and repetitive situations, for example, automated coin-box photography, it is important for the photographer to be able to anticipate the effect of the flash on the subject or object prior to taking the photograph. There are several different approaches to correct the weaknesses or limitations characteristic with the use of electronic flash as the sole light source.
One solution involves the use of instant materials, for example, Polaroid films, to check the lighting. This is advantageous since this check includes the camera and optics as well as the lighting. In situations requiring many light sources, such checks are both costly and time consuming and may result in a lost photograph if the object moves in an uncontrollable manner and the action cannot be duplicated.
Another solution attacks the problem more directly. It involves the placement of a continuous light source, for example, a tungsten-halogen bulb, symmetrically within a helical or annular flash tube and mounting the combination symmetrically within the same reflector. A further refinement is the use of a diffusing envelope to enclose both the flash and continuous source to provide even more accurate modeling. Furthermore, power supplies for such lamp heads often have provision for varying the intensity of the flash and for varying the intensity of the modeling light, in proportion to and independently of the flash output. In addition, several such lamp heads may be connected to the same power supply since compared to early generators, modern power supplies offer large power output in a relatively small, light weight and inexpensive package.
The importance of these developments to the production of high quality photographs in a reasonable time is attested to by their acceptance by the photographic community. However these developments are primarily designed and used for photographing relatively large objects. In the range of image size to object size of 1:10 to 1:1 such units are used, however there is still a need for more controlled lighting in small areas.
At magnifications greater than the ratio of image size to object size of about 40:1, that is in the microscopic region, various light sources and reflectors are known to provide light for visual and photographic purposes. Unlike the broad sources often used in large object photography, a principal requirement here is to produce an extremely intense beam in a small area. Most of these employ a continuous light source of small size in combination with various condensing lenses. To overcome excessive heat at the object surface, illuminators using fiber optics to bring light to the object, with the source removed from the immediate area, have been successfully employed. Some of these illuminators use both an electronic flash and a continuous source, both totally directed onto a single fiber optic bundle of small diameter (typically 1/16" to 1/8" in diameter). Such units are very specialized lights, using small diameter fiber bundles having one bundle per light source and, in general, they are designed for microscopic use.
Although photographic hardware includes macro lenses for single lens reflex cameras, apochromatic lenses for use at and near 1:1 magnification, and special lenses for use in the range of magnifications from 1:1 to 40:1 including special photographic stands for using these lenses with small and large format films, lighting for this type of photography has been exceedingly limited, requiring great skill, ingenuity and time to produce acceptable photographs. Consequently, light sources employed in other areas of photography are called into use and illuminators designed for visual inspection are even sometimes called upon to expose film.
The disadvantages of using nonflash or continuous light for photographing objects within the image to object range of greater than 1:1 are that it produces a high heat output in a confined area, involves a relatively high cost for multiple lights, and entails difficulty in maneuvering multiple lights in a confined area. In addition, long exposure times which are generally required often necessitate costly anti-vibration equipment and result in a restricted ability to photograph mobile living material.
The use of fiber optics with a continuous source solves the heat and maneuverability problems but the other problems remain. Several commercial fiber optic illuminators are capable of using a plurality of bundles from a single continuous source, usually a tungsten-halogen bulb. These units generally control intensity of the light by varying the voltage. This is acceptable for visual inspection and black and white films, however, changing the voltage changes the color temperature of the source so that such units are extremely cumbersome for use with color films. Similarly, those sources employing fluorescent tubes and discontinuous arc sources are very difficult to use with color films where critical color is important.
One of the principal difficulties with photography in the image to object magnification range of 1:1 to 40:1 is that many of the objects can be considered 3-dimentional as opposed to the 2-dimensional nature of microscope slides and thin sections. The 3-dimensional aspect coupled with very little depth of field means that accurate lighting is often necessary to help delineate the object. Accurate lighting in this case means the ability to control the placement of highlights and shadows and their intensities within a small area. Furthermore, if the object is of a complicated shape, many lights may be necessary to achieve optimal photographic results. Consequently, these considerations lead many photographers to use a continuous light source, despite its disadvantages, in preference to flash sources which do not provide for accurate modeling.
Those illumination sources using an electronic flash which have been designed for close-up photography and which are used at 1:1 and up to about 3:1 may be divided into three basic types, as well as a bare bulb flash placed close to the object. The first type is called a ring light and consists of a circular flash tube positioned so that the lens is in the center of the tube and the optical axis is perpendicular to the plane of the flash tube. Ring lights are designed to illuminate cavities and to provide a shadowless light, i.e., they provide one important photographic control at the lower magnifications for certain shaped objects. These units come in various sizes and some have one or two small continuous light sources attached which are primarily used as focusing aids and not as modeling lights. One variation of this type of light source consist of four flash tubes arranged around the perimeter of a square rather than a circular enclosure such that each side of the square has a small continuous light which could give some approximation of the flash effect. A recent advance in this type of light source for use with a 35 mm camera has been to incorporate an auto flash system along with the ring light, again without a modeling light.
A second type involves the use of one or two small portable electronic flash units mounted in a more or less fixed orientation with respect to the lens. Some such set-ups use automatic flash units where a sensor restricts the duration of the flash as the flash to object distances decreases. This is less than desirable for critical color work because of reciprocity effects due to very short flash durations. Such set-ups offer convenience at the expense of control, and again, there is no modeling source involved.
The third type of light which is available is the focusing spot light which uses both electronic flash and a continuous source for viewing. These units are rather large and somewhat difficult to manipulate in small increments. It is an excellent light in the lower magnification but does not in itself solve the problems throughout the range of magnifications required.
A recent commercial fiber optic device consists of a fiber optic ring light connected to a continuous light source. With this arrangement a person can properly view the effect of the ring light, however, a flash source is not employed.
A practical difficulty with providing an entirely new source of illumination involves its expense. Ideally, a new illuminator would employ as much existing technology as possible so that the photographic studio or laboratory could add the new source to existing equipment in an modular way. Alternatively, the new illuminator would be such that it could easily be adapted for use in other applications, for example, close-up photography and photomicrography.
An object of the present invention is to provide a dual light source apparatus for illuminating a diffusion dome and wherein at least one fiber optic bundle is disposed within a specific area on the diffusion dome so that the light illuminated through the diffusion dome to the fiber optic bundle can be used as a modeling light source for illuminating small objects which can then be photographed and/or observed.
Another object of the present invention is to provide a dual light source apparatus for illuminating a diffusion dome which can accommodate a plurality of the same size or different size fiber optic bundles within a specific area on the diffusion dome so that the light illuminated through the diffusion dome to the fiber optic bundles can be used to illuminate one or more objects.
Another object of the present invention is to provide a dual light source apparatus for illuminating a diffusion dome which, in turn, is coupled to at least one fiber optic bundle disposed within a specific area of the diffusion dome so that the light from the dual light source transmitted through the fiber optic bundle can be used to illuminate an object for observation and/or photography.
Another object of the present invention is to provide a dual light source and fiber optic bundle illuminator which provides a fairly uniform intensity distribution in the light emanating from the fiber optic bundle without a central intense hot spot and without halos of great intensity even though the sources of light are from a modeling light source and a flash light source.
Another object of the present invention is to provide an illuminator employing a dual light source coupled to fiber optic bundles which can provide a photographer with the variety and control of lighting normally available for large object photography for use in the area of small object photography.
Another object of the present invention is to provide an illuminator for photographic and visual work in the range of magnifications from about 1:1 to about 40:1 which employs both an electronic flash and an accurate modeling light so that the chief benefits of the flash illumination can be enjoyed without the disadvantage of an inaccurate modeling light or no modeling light at all.
It is another object of this invention to couple a dual light source with finer optics and thereby enjoy the benefits of using fiber optic bundles(s) to carry the light to the subject/object.
It is another object of this invention to demonstrate a manner and method of interfacing a dual light source with fiber optic bundle(s) so that the light emitted by the fiber optic bundles(s) may be used for the purposes referred to above.
The foregoing and additional objects will become more fully apparent from the following description.